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Part II: Network Users, Resources, and Special Server Roles


Hour 7 Working with the TCP/IP Network Protocol


Hour 8 Understanding and Configuring Active Directory Domain Services


Hour 9 Creating Active Directory Groups, Organizational Units, and Sites


Hour 10 Adding Client Computers and Member Servers to the Domain


Hour 11 Deploying Group Policy and Network Access Protection


Hour 12 Working with Network Shares and the Distributed File System


Hour 13 Understanding Share and NTFS Permissions


Hour 14 Working with Network Printing


Hour 15 Understanding the Domain Name Service


Hour 16 Using the Dynamic Host Configuration Protocol

Hour 7. Working with TCP/IP Network Protocols

What You’ll Learn in This Hour:

This hour looks at the ins and outs of the TCP/IP protocol stack. The IP protocol has become the de facto (really the only) protocol stack for networking because of the need for network connectivity to the Internet. This hour also looks at the basics of IPv4 subnetting and issues related to implementing IPv6 on a network. The discussion also includes the OSI model (the conceptual model for network protocol stacks) and TCP/IP configuration issues on domain servers and domain clients.

Understanding Network Protocols and the OSI Model

From the genesis of computer networking to the high-speed TCP/IP LANs and WANs that we work with today, network protocols have provided the rules for how computers communicate on a network. Most network protocols are typically not single protocols, but a stack of specialized protocols that work together. Some of these member protocols in the stack are responsible for the user interface and network connections necessary to move the data. Other member protocols in a stack actually address the data (to get it to the right destination). Still others provide the mechanism for transporting the data to and from places on the network.

A number of different protocol stacks have come and gone over the years. NetBEUI (which was designed for workgroups) was once a popular network protocol for small Microsoft networks, and networks using Novell’s SPX/IPX protocol stack were the rule during Novell’s dominance of the networking arena. With the development of the Internet infrastructure over the last 30 years, the TCP/IP protocol stack has become the dominant protocol stack for all sizes of networks from the small office or home workgroup to extremely large corporate domains.

By the Way

IPX/SPX (which stands for Internetwork Packet Exchange/Sequenced Packet Exchange) is a network protocol stack developed by Novell for use on networks running early versions of the Novell NetWare network operating system (NetWare now uses TCP/IP as its default networking protocol). NWlink is Microsoft’s implementation of IPX/SPX, and was used on network clients and servers in situations where a mixed network of Windows and Novell servers both existed on the network.

Understanding a rather complex protocol stack such as TCP/IP can be aided when the real world protocol stack, in this case TCP/IP, is compared to a conceptual model that provides insight into what each protocol layer in the TCP/IP stack is actually responsible for. In the late 1970s, the International Standards Organization (ISO) began to develop a conceptual model for networking called the Open Systems Interconnect Reference Model. This is now commonly abbreviated as the OSI model. In 1983, the model became the international standard for network communications, providing a conceptual framework that helps explain how data gets from one place to another on a network.

The OSI model describes network communication as a series of seven layers; each layer is responsible for a different part of the overall process of moving data. This framework of a layered stack, while conceptual, can then be used to understand how actual protocol stacks work when data moves from a sending computer to a receiving computer. So don’t think of the model as a series of layers, but rather as a stack of protocols, with each protocol handing off the data to the next protocol in the stack.

Table 7.1 provides a list of the OSI model layers from the top of the stack to the bottom, with a brief description of each layer. The layers are actually numbered from bottom to top and are often referred to by the layer number (in discussions related to the OSI model). Data moves from the sending computer down the OSI model stack. Then, when it is received by the receiving computer as a bit stream, the data moves back up the model until it is in a form that can be understood by the receiving user (such as an email message).

Table 7.1. The OSI Layers
Layer Number Layer Function
7 Application Provides the interface and services that support user applications and provides general access to the network.
6 Presentation The translator of the OSI model. Responsible for the conversion of data into a generic format and the coding of data using various encryption methods.
5 Session Establishes and maintains the communication link between communicating computers (sending and receiving).
4 Transport Responsible for end-to-end data transmission, flow control, error checking, and recovery.
3 Network Provides the logical addressing system that is used to route data from one node to another, meaning that it is responsible for path determination.
2 Data Link Responsible for framing of data packets and the data movement across the physical link between two nodes.
1 Physical Manages the process of sending and receiving bits over the physical network media (the wire and other physical devices).

A protocol stack such as TCP/IP can be mapped to the OSI model. This enables you to understand the general purpose of each protocol in the TCP/IP stack. Let’s take a look at the TCP/IP stack and then we can tackle some specifics related to configuring TCP/IP on a server and working with IP addressing.

By the Way

The TCP/IP protocol suite was actually developed before the OSI model was created. In fact, a model known as the Department of Defense (DOD) model was used in the development of TCP/IP. Despite these facts, the OSI model is still used today to explain how the different protocols in the TCP/IP stack function in the sending and receiving of data on a network.

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